The interactive computer-based staircase scaling method and the continuous track-ball method were each used in two experiments. One track-ball study delivered 1.4 sec 49 degrees C thermal stimuli, the other studies delivered stimuli, ranging from 37 to 53 degrees C. The first experiment is providing additional evidence that cardiac chest pain in patients with normal coronary arteries does not represent general hyperalgesia and is actually accompanied by reduced somatic pain sensitivity. The second experiment is examining the effects of imipramine and clonidine on the perception of painful thermal stimuli in this group of patients. The code will not be broken in either study until a total of 60 patients is completed for each. The third study used the track-ball method to assess the effects of fentanyl or placebo on the magnitude and duration of pain sensations evoked by 3-sec thermal stimuli of varying intensity. A preliminary analysis of 40 subjects shows that fentanyl reduces both the magnitude and durations of thermally-evoked pain sensations. The fourth study used track-ball assessment of trains of 49 degrees C stimuli to assess the effects of fentanyl on first and second pain sensations. New computer programs are required for a preliminary analysis.